Method of flameproofing combustible cellulosic material



Patented June 7, 1949 METHOD OF FLAMEPROOFING COMBUS- TIBLE CELLULOSICMATERIAL Andrew McLean, West Kilbride, and Stanley Frederic Marrian,Ardrossan, Scotland, assignors to Imperial Chemical Industries Limited,a corporation of Great Britain No Drawing. Application rial No. 628,994.In Great Britain January 10,

November 15, 1945, Se-

6 Claims. (Cl. 117-137) The present invention relates to a new orimproved method of flame-proofing combustible cellulosic materials thatenables them to be washed or laundered in hot aqueous media'withoutlosing their flame-proof qualities, and to the resulting fiame-proofedcellulosic materials. The invention also relates to a new reagent foruse as a flame-proofing component according to the aforesaid new orimproved method of flame-proofing combustible cellulosic materials.

Amongst the cellulosic materials to which the invention is especiallyapplicable are textile fabrics, for instance woven or pleated fabrics,threads, yarns, filaments, and fibres, made of cotton, linen,regenerated cellulose, jute, cellulose acetate, and the like.

Various proposals have already been made in connection with theflame-proofing of combustile materials but these proposals for the mostpart have suilered from such disadvantages as the necessity of having toemploy large amounts of reagent to ensure effective flameproofingthereby stiifening the materials to an undesirable extent, thedifliculty experienced in fixing the reagent satisfactorily to thecombustible materials so that it will resist laundering operations, andthe scarcity or difliculty of production of some of the reagentsproposed.

A process has already been disclosed which comprises treating with anacidic-flre-retardant as for example phosphoric acid or calcium phytatea cellulosic material impregnated with polyethyleneimine.

An object of the present invention is to provide a method offlame-proofing combustible cellulosic materials, and a newflame-proofing component used in carrying out the method, yieldingflame-proof products that retain their flame-proof qualities subsequentto hot water washing and laundering with hot soap solutions in a moresatisfactory degree than heretofore.

It has been found that compositions comprising the novel compoundpentaerythritol tetraorthophosphate can be readily anchored tocellulosic materials impregnated with a polyethyleneimine to giveflame-proof cellulosic materials which retain their flame-proofcharacteristics subsequent to their treatment with soap and waterwashing.

According to the present invention therefore the method offlame-proofing combustible cellulosic materials comprises treating thesaid materials impregnated with .a polyethyleneimine with a solutioncomprising pentaerythritol tetraorthophosphate.

The flame-proofing component according to the present invention" forflame-proofing combustible cellulosic materials previously subjected tothe action of a polyethyleneimine comprisespentaerythritol-tetra-orthophosphate.

Crude pentaerythritol tetra-orthophosphate was prepared frompentaerythritol, ortho-phosphoric acid and phosphorus pentoxide asfollows, the quantities employed being based upon the molecular ratio ofthree parts pentaerythritol, four parts of ortho-phosporic acid and fourparts phosphorus pentoxide.

Phosphoric acid (11 gr. of 88%) was added gradually to phosphoruspentoxide (25 gr.) and when the mixture was cool, pentaerythritol (15.3gr.) was added thereto, the whole being well stirred. The mixture washeated in an oil bath at -130 C. for 20 hours with exclusion of moistureand occasional stirring. The crude pentaerythritol tetra-orthophosphateproduct thus formed probably contained phosphoric acid andpentaerythritol tri-, diand monoorthophosphate in addition to thepentaerythritol tetra-orthophosphate.

Comparative experiments were carried out to illustrate the differencesin behaviour to washing with soapand water of cotton cloth in every casefirst treated with an aqueous solution of polyethyleneimine in themanner specified and subsequently with aqueous solutions of the crudepentaerythritol tetra-orthophosphate, an aqueous solution of a mixtureof the three reactants upon which the heat treatment was omitted, themixture being immediately dissolved in water, and an aqueous solutiondiluted as required of a mixture of. phosphoric acid and phosphoruspentoxide only which were heated together before dissolving in water.Solutions of various concentrations were used.

Experiments were also carried out to see how to improve the handle orfeel of the combustible cellulosic materials and yet retain the desiredfireproof qualities after soap and water washing.

The handle or feel is found to be often improved by cutting down thequantity of polyethyleneimine with which the combustible cellulosicmaterials is impregnated, as for example by working withpolyethyleneimine solutions of strengths lower than 8-12 per cent, butto make certain that in such cases the product remains flame-proof aftersoap and water washing it is often necessary to treat it subsequent tothe pentaerythritol tetra-orthophosphate treatment with an acidifiedaqueous solution of hexamethoxymethyl melamine or triethoxymethylmelamine followed by baking at about 100 C. The said acidification canbe efiected for ex-' ample with paratolueue sulphonic acid.

A piece of cotton cloth (12 sq. ins.) was soaked in 10 ml. or a boilingaqueous solution of polyethyleneimine for one hour, wrung out and bakedin a steam oven overnight. The clot-h was then steeped in 15 ml. of anaqueous solution of the crude pentaerythritol tetra-orthophosphate forone hour at room temperature, thoroughly rinsed, and dried. The timegiven for each operation and the quantities used were arbitrarily fixed.

Testing of fiame-proofness was carried out by holding the cloth in aBunsen flame for 5-10 4 impregnated with an aqueous 8% to 12%polyethyleneimine solution.

3. A method as claimed in claim 1 wherein the cellulosic materials aresubsequently treated with an acidified aqueous solution of a compoundfrom the group consisting of hexamethoxymethyl melamine andtriethoxymethyl melamine, followed by baking at about 100 C.

4. A method as claimed in claim 3 wherein the compound selected ishexamethoxymethyl melamine.

5. A method as claimed in claim 3 wherein the compound selected istriethoxymethyl melamine.

' 6. Flame-proofed combustible cellulosic textile seconds. Some charringalways took place, but if 15 m i l imp w h p yethylenimine and burningwas not propagated with any speed in containing pentaerythritol.tetra-orthophosphate the flame and ceased without afterglow when as theflameprmfing compimentthe cloth was removed from the flame, the clothANDREW MCLEAN. was recorded as flame-proof. If either of these STANLEYFREDERIC MARRIAN. conditions was not satisfied the sample was recordedas not flame-proof. REFERENCES CITED The stability of the flmeqn-oofness to wash- The following references are of record in the ingwas tested as follows: The test piece was me of this Patent: stirredwith 2:0 :11. 1iiv later at 4(fJ-50" C. forh T UNITED STATES PATENTSminutes and rie ame-proo ness was t en tested as above. The same piecewas then stirred Number Name Date 1,660,651 Marshall et a1 Feb. 28, 1928with 200 ml. of 0.25 per cent soap solution at 2,071,353 Morgan Feb, 23,1937 40-50 C. for 30 minutes, wrung out, rinsed thor- 2,286 726 GordonJune 16 1942 oughly in 3 changes of water and dried. The 30fiame-proofness was again tested. FOREIGN PATENTS The results obtainedare given in .the following Niunber Country Date table: 476,043 GreatBritain Apr. 27, 1936 Bar Alta W is Alte s was i g Wa shlgg r Water $5331;

1: l i i n i fiiifiihiiififilfiifii. i$ 5231 1 Billion. f'ffifffff:?fff: fiiiififilfi'aor 109g polyethyieneimine, l a control 1 iiquor. d D10% polyethyleneimine, 10% phosphoric acid.. a 9 polyethyleneiminc, 8%p. t. p ilameproor. 3 polyethylencimme, 8% phosphoric acid. notllameprooi. 4 7 polyethyienei nine, 4 Do. 4 ,polyethyieneimine, 4%hosphoric aci Do, 5,polyothyleneimine, 1 p. t. Do. 59 polyethyieneimine,10% p t. p. Final treatment with a solution containing 2 gramsilameprooi examethoxymethyl melamme+0.05 grams 1. toluene sulphonic acidin 18 cc. water (ior l2 sq. ins. cloth) followed by baking at 100 C. for1 hour). %L"Lii'ii:2$ii.3it' ittifiifiiith iii i r iothfgllow ed bybaking at 10% ice l hour. p M n cc wawr (or 12 sq' ms.

p. t. p.=pentaerythritol tetra-orthophosphate.

1 Solution of unheated mixture oi pentaerythritol, phosphoric acid and ISolution of heated mixture of phosphoric acid and phosphorus pentoxidphosphorus pontoxide. e.

OTHER REFERENCES Chem. Abstracts. vol. 38, p.

Chem. Abstracts, vol. 32, p.

